Clamping device



May 12, 1931. v. E. WALTERS ET AL CLAMPING DEVICE Filed May 12. 1928 2Sheets-Sheet 1 y 1931- v. E; WALTERS ET AL ,443

CLAMPING DEVICE Filed May 12. 1928 2 Sheets-Sheet 2 Patented May 12,1931' UNITED STATES PATENT OFFICE "VERNON E. WALTERS, OF DETROIT, ANDIRVING GRANT, OF GROSSE POINTE PARK, MICHIGAN, ASSIGNORS TO GENERALMOTORS CORPORATION, OF DETROIT, IICHIGAN,

A CORPORATION OF DELAWARE CLAMI'ING DEVICE Application filed Kay 12,1928. Serial No. 277,285.

This invention relates to a clamping device used for holding an articlewhile some machining operation such as drilling, grinding, milling, etc.is being performed.

In factories where machine work is done on a large production basis, itis desirable to have a simple clamping device into which the work to beheld may be quickly inserted or withdrawn from. The clamping orunclamping action must be obtained by a single movement of. theoperating lever, and t e work must be positively held so that it is notpermitted to move while the machining operation is being performed. v

There are a number of clamping fixtures available in which the clampingaction is produced by a compression spring. These, however, are notsatisfactory due to the fact that the article being worked on is notpositively held as the resiliency of the spring sometimes permits acertain amount of movement of the article while it is being-machined,thus resulting in inaccuracies.

An object of this invention is to prov de such a device in which theclamping actlon is obtained by means of cam-shaped surfaces which engageeach other to produce a wedging action. This wedging action also servesto hold the fixture in clamping position. To

further insure that the fixture will be positively held in clampingposition a compression spring is provided which cooperates with thecam-shaped surfaces to assist in producing the locking action.

Other objects and advantages will be apparent upon referring to thespecification and accompanying drawings in which Figure 1 is a verticalsection through our improved clamping device.

Figure 2 is a section taken on the line 22 of Figure 1.

Figure 3 is a plan view of the device with parts broken away. a

Figure 4 is a detailed perspective view of one of the parts.

Figure 5 is a detailed perspective view of another of the parts.

Figure 6 is a section taken onthe line 6-6 of Figure 2. p

Figure 7 is a section taken on the line7-7 of Figure 1.

Figure 8 is a developed view of a spiral groove'in one of the parts.

Figure 9 is a section taken on the line 9-9 of Figure 1.

The reference number 10 indicates a base or fixed member having avertical passage 12, in which is mounted a sleeve 14. On the outsideofthis sleeve, teeth 16 are milled across one side as shown in Figure 7.Supported on a shaft 18, which is journaled in the base, is a pinion 20,which is held to the shaft by a key 22. The pinion 20 has teeth 24formed on it, which mesh with the teeth 16, and prevent the sleeve 14from rotating within the passage 12. A handle 26 is secured in the shaft18, and the latter is held in place in the base by means of a pin 28.

Mounted in the sleeve 14 is a vertical shaft 30, which is eccentricallylocated in the sleeve in order that the teeth 16 may be cut in thelatter without weakening it.- The shaft 30 has formed in it a spiralgroove 32, which is provided with an offset or shoulder portion 34 atits upper end as shown in Figure 8. A set screw or pin 36, which issecured in' the sleeve 14, has a reduced end portion which fits into thegroove 32, and when the device is in imclamped position, this endportion is held at the upper end of the groove by being held behind theshoulder 34, so that the sleeve 14 and the shaft 30 will move up or downas a unit and in order that the shaft 30 may not rotate within thesleeve 14.

Secured against a shoulder 37 at the -upper end of the shaft 30 is acollar 38. A thrust bearing 40 isheld in the collar by means of a cap42, which is retained by the nuts 44. The shaft 30 is free to turnwithin the collar 38, and the function of the bearing 40 is to take thethrust loaddeveloped by the clamping action to be described later. Asupport 46 is mounted upon the outside of the collar 38, and has securedto it by means of guides 47 and nuts 49, an upper clamping member ormovable member 48. The guides 47 extend down into passages 51 in thebase 10, and

. serve to hold the movable member 48 in proper relation to the base, aswell as to prevent rotation of the movable member 48.

Y larger than that shown, the support 46, to-

gether with the movable member 48 may be moved upward relative to thecollar 38, by loosening the hollow-headed screw 58,- which releases asleeve 60 which is normally drawn a ainst the collar 38 as shown inFigure 6. Vllhen the sleeve 60 is in released position, the support 46may be freely moved up or down with respect to the collar 38, tocorrespond with the size of the work which it is desired to clamp.

Secured in the bottom of the base 10 is a ring member 62 which is heldin place by screws 64 which are threaded into the base and which fitinto grooves 66 in the ring member to prevent rotation of the latter.This ring member has formed on it cam or inclined surfaces 68, as shownin Figure 5. The lower end of the shaft has formed on it extensions 70and, 72, the upper sides of which are shaped to form cam or inclinedsurfaces 74, as shown in Figure 4. When the fixture is in unclampedposition, the extensions 70 and 72 are held in such position by the pin36 fitting into the shoulder 34 in the spiral roove, that theseextensions may pass throng slots 76 in the ring member 62. Secured inthe bottom of the base 10, as best shown in Figure 9, is a pin orset-screw 78, which has a portion of its inner end cut away to providean angular face 80. Surrounding the shaft 30, and held by the sleeve 14and the collar 38, is a compression spring 82.

The operation of the device isas follows: The operator places the workwhich is to be machined, such as the connecting-rod 50, in thework-supporting member 52, and turns the handle 26 in acounter-clockwise direction as viewed in Figure 1, thereby rotating thepinion 20, causing the sleeve 14 and the shaft 0 to be moved downwardly.

- The extensions 70 and 72 at the lower end of the shaft 30 pass-throughthe slots 76, and continue in their downward movement until a chamferedportion 71 on the extension 70 strikes the angular face of the set-screw78. This, of course, tends to cause the shaft 30 to rotate in aclockwise direction as viewed in Figure 9. This rotation of the shaft 30causes the pin 36 to be disengaged from the shoulder 34 in the spiralgroove 32. The shaft 30 is-novyfree to rotate and move axially-withrespect to'the sleeve 14. The compression spring 82 tends to force thesleeve 14 downwardly, and due to the action on the pin 36 working in thespiral groove 32, the shaft 30 is caused to rotate 1n such direction aswill cause the inclined surfaces 74 to become wedged against theinclined surfaces 68. At this time, of course, the movable member 48 hasbeen brought down to a position whereby the connecting-rod is clampedtightly between the work-sup orting members 52 and 54. The angle of theinclined surfaces 68 and 74 is so chosen that the proper clamping actionis obtained without any possibility of the parts becoming so wedgedtogether that they may not be readily released by taming the shaft 30 inthe opposite direction, and so that a comparatively large range ofclamping movement is provided. It is not necessary that the surfaces 74be moved to any particular position with respect to the surfaces 68. Theclamping action will be obtained any time that the inclined surfaces 74engage any part of the inclined surfaces 68. Therefore, the range ofclamping action for any setting of the movable member with respect tothe collar 38 will be substantially equal to the height of the inclinedsurfaces 68. This permits the device to be used for clamping work whichis apt to vary considerably in size, without changing the setting of theclamping device, and at the same time securing .the same clampingpressure with each piece of work.

When it is desired to unclamp the device, the handle 26 is moved in theopposite direction, thereby pulling up the sleeve 14. Due to the actionof the pin 36 in the spiral groove 32, the shaft30 is rapidly rotated ina direction which will disengage the inclined surfaces 74 from thesurfaces 68. Just as the shaft 32 reaches its normal position, chamferedportions 84 on the inclined surfaces 74 come into contact with similarchamfered portions 86 formed on the inclined surfaces 68, for thepurpose of forcing the pin 36 into position behind the shoulder 34 inthe spiral groove 32, so that the shaft 30 will a ain be locked inposition in the sleeve 14.

ontinued movement of the handle 26 then causes the sleeve 14, shaft 30and movable member 48 to be moved to their uppermost ositionso that thework may be removed.

e arts are held inthis position by the weig t of the handle 26, which isso designed that due to the ratio of the gears, it more than offsets theweight of the movable member 48 and associated parts.

It will be readily seen that the clamping action is obtained through thewedging tendency of the inclined surfaces 68 and 74 upon each other, andthat the only function of the spring 82 is to aid in holding the inclinesurfaces in clamping position, so that they may not work loose due tovibration.

Thus there is no possibility of the clamping device accidentallyloosening while the work is being machined, thereby resulting in indrillpress or other machine on which it is being used, that the clampingaction will be automatically obtained w brought into operating position,and the unclamping action will be obtained by turning the controllingmechanism to the shuttingoif position.

It is thought from the foregoing, taken in connection with theaccompanying drawings, that the construction and operation of the devicewill be apparent to those skilled in the art, and that various changesin size, shape and pro ortion, and details of construction may e madewithout departing from the spirit and scope. of the appended claims.

We claim:

1. A clamping device comprising, in combination, a fixed member, amovable member, an axially movable sleeve carried in said fixed member,a shaft connected to said movable member and rotatably and axiallymovable in said sleeve, inclined surfaces on said fixedmember, inclinedsurfaces on .said shaft, means to move said sleeve, shaft and movablemember toward said fixed member, and connecting means between said shaftand sleeve so constructed that axial movement of the sleeve causesrotary and axial movement of said shaft in said sleeve to cause saidinclined surfaces to become engaged for the purpose of producing aclampin action between said fixed and movable mem ers.

2. A clamping device comprising, in com-.

bination, a fixed member, a movable member, an axially movable andnon-rotatable sleeve carried in said fixed member, a shaft connected tosaid movable member and rotatably and axially movable in said sleeve,means to lock said shaft in said sleeve when the device is in lmclampingposition, inclined surfaces on said fixed member, inclined surfaces onsaid shaft, means to move said sleeve shaft and movable member towardsaid fixed member, means to unlock said shaft from said sleeve when saidshaft is in substantiallyits lowermost position, and means to rotatesaid shaft in said sleeve to cause said inclined surfaces to becomeengaged for the purpose of roducing a clampin action between said ed andmovable mem rs.

Isleeve at the beginning en the machine is -to produce a clamping action3. The combination as defined in claim 2, and means to again lock saidshaft in said of the movement which will return the device to unclampingposition.

4. A clamping device comprising, in combination, a fixed member, amovable member, a shaft connected to said movable member, a sleeveaxially movable but non-rotatable in said fixed member, said shaft beingaxially and rotatably movable in said sleeve, means to move said sleeveand shaft toward said fixed member, inclined surfaces on both said shaftand said fixed member, means to rotate a said shaft in said sleeve atsubstantially the lowermost point of travel of said shaft so that saidinclined surfaces enga e each other between said fixed and movablemembers, and spring means operative only when the parts are in clampingposition to tend to rotate said shaft for the purpose of causing saidinclined surfaces to become more tightly engaged.

5. A clam ing device comprising, in combination, a fixed member, amovable member, an axially movable sleeve carried in said fixed member,teeth formed in said sleeve, a pinion meshing with said teeth andserving to prevent rotation of said sleeve, a shaft connected tosaidmovable member and r0- tatably and axially movable in said sleeve, aspiral groove havinga shoulder at its upper end formed in said shaft, apin secured in said sleeve, the end of said pin fitting into said grooveand being normally held by said shoulder, a compression spring betweensaid movable member and said sleeve, inclined surfaces on said fixedmember, inclined surfaces on said shaft, and a deflecting member held insaid fixed member and adapted to release said pin from said shoulder andto rotate said shaft when said sleeve is moved to substantially itslowermost position by said pinion so that said inclined surfaces willengage each other to produce a clamping action between saidfixed andmovable member, said spring serving to assist in holding said inclinedsurfaces in clamping position through the action of said pin and saidspiral groove.

In testimony whereof we afiix our signatures- VERNON E. WALTERS. IRVINGGRANT.

